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Explore the nuclear structure of fission fragments using GRETINA/CHICO2 . GRETINA User Workshop, Argonne National Lab. March 1, 2013. Ching-Yen Wu. Gammasphere /CHICO at ANL, 2008. Gammasphere /CHICO setup in front of FMA. 178 Hf on 208 Pb at E lab =984 MeV. TOF vs position. - PowerPoint PPT Presentation
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LLNL-PRES-624013This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract
DE-AC52-07NA27344. Lawrence Livermore National Security, LLC
Explore the nuclear structure of fission fragments using GRETINA/CHICO2
GRETINA User Workshop, Argonne National Lab
Ching-Yen Wu
March 1, 2013
Lawrence Livermore National Laboratory LLNL-PRES-pending2
Gammasphere/CHICO at ANL, 2008Gammasphere/CHICO setup in front of FMA 178Hf on 208Pb at Elab=984 MeV
TOF vs position
Doppler-shift corrected spectrum
E (keV)
Lawrence Livermore National Laboratory LLNL-PRES-pending3
Precision Doppler-shift correction
Raw data
Corrected for U-like particles
Corrected for Er-like particles
1358 MeV 238U on 170Er; Phys. Rev. C61, 21305(R) (2000)
Lawrence Livermore National Laboratory LLNL-PRES-pending4
144Ba on 208Pb
92Zr on 208Pb
Two-body kinematics for 144Ba experiment
Beam contamination such as 92Zr and 92Mo can be removed
Lawrence Livermore National Laboratory LLNL-PRES-pending5
LLNL/Rochester physics program – radioactive beam
Prolate to oblate (shape) transition• Shapes in 110,112Ru and 114,116Pd; measured by the sign of electromagnetic static
matrix element• H. Hua, C.Y. Wu, D. Cline et al., PLB 562, 201 (2003)
Spherical to deformed (shape) transition• Shape coexistence in Sr-Zr isotopes• Deformation in 98,100Sr and 100,102,104Zr; measured by the magnitude of
electromagnetic transition matrix element
Evolution of octupole (collectivity) in Ba (A=144 and 146) isotopes isomerism
ANL Workshop 4/8/2006
Lawrence Livermore National Laboratory LLNL-PRES-pending6
Systematics of Pd isotopes with A 110
Mass Eex (2+) (keV)
108 434
110 374
112 349
114 333
116 340
118 379
Shape transition from prolate to oblate for the Pd isotopes predicted to occur at 111Pd by the finite-range droplet model (P. Moller et al., At. Data Nucl. Data Tables 59, 185 (1995) and 112Pd by the relativistic mean-field theory (G.A. Lalazissis et al., At. Data Nucl. Data Tables 71, 1 (1999)
Lawrence Livermore National Laboratory LLNL-PRES-pending7
Case study – shape measurement for 116Pd
116Pd on 1 mg/cm2 208Pb at ELab = 400 MeV M(E2; 2+ 0+) = 0.76 eb, M(E2; 2+ 2+) = − 0.72 eb
lab (degrees) Yield (2+0+) (mb) Pro/Obl
bin size Prolate Oblate
45 5 60.4 71.0 0.85
55 5 45.1 56.2 0.80
65 5 31.6 41.6 0.76
115 10 8.29 12.5 0.66
130 10 3.72 5.66 0.66
145 10 2.46 3.76 0.65
Lawrence Livermore National Laboratory LLNL-PRES-pending8
Case study
Beam intensity: 116Pd – 8.1 x 104 pps (CARIBU proposal) Calculation assuming 104 pps GRETINA efficiency ~ 30% at E = 340 keV 23 counts/day for = 145o (10o bin) Statistics better than 10% obtained with 5 days of beam-on-
target Alternative: 116Pd on 58Ni to reduce the burden of analysis Applied for 110Ru (3.6 x 105 pps), 112Ru (9.2 x 104 pps), and 114Pd
(1.8 x 105 pps)